Postage machines are well known and in common use. A classic postage meter is composed of a memory representing stored postage value, and a printing mechanism for printing postage indicia on mail pieces, all in a secure housing. It has also been proposed to use what is termed a "postal security device" or PSD, connected via a nonsecure communications channel with a nonsecure printer, as a substitute for a classic postage meter. The PSD has a secure housing, and encrypted information is communicated from the PSD to the printer for printing as part of the postage indicia. It has also been proposed to use a PSD connected via nonsecure communications channels such as local-area networks, to a plurality of printers for printing of such indicia.
With any of these arrangements the postage meter or PSD (referred to collectively herein as postage metering devices) contains accounting registers. The accounting registers may be pure mechanical registers in a pure mechanical postage meter, in which the postage value is stored by physical positions of gears and shafts. The registers may be nonvolatile semiconductor memories in the case of an electronic postage meter or a PSD. In any of these arrangements, the practical situation is that there is stored value in the metering device, and that stored value can be put to use only by the printing of postage value on mail pieces, or in the exteme case by taking the metering device out of service and requesting a refund from the postal authority.